Bio 321 F13 lecture 3 v2

Varies among species 3 types of tsd slide from j

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Unformatted text preview: portion of males" 1.0" Intermediate" temp., both sexes" 0.5" High temp., " all females" 0" 20" 40" Temperature ºC" slide from J. Wiens TSD/GSD" TSD--Pattern Ia" (this pattern is found in most turtles)" Proportion of males" 1.0" 0.5" 0" 20" 40" Temperature ºC" slide from J. Wiens TSD/GSD" TSD--Pattern Ib" (some lizards)" Proportion of males" 1.0" 0.5" 0" 20" 40" Temperature ºC" slide from J. Wiens TSD/GSD" TSD--Pattern II" (crocodilians, some turtles and lizards)" Proportion of males" 1.0" 0.5" 0" 20" 40" Temperature ºC" slide from J. Wiens Turtle phylogeny! based on molecular data ! (Krenz et al. 2005)! Trionychid ae" Geoemydid ae" Testudinida e" Emydida e" Carretochelyid ae" Cheloniid Kinosternidae" ae" Dermochelyid Dermatemydid ae" ae" Chelydrida e" Platysternonida e" Podocnemidae" Pelomedusidae" Chelidae" TSD! GSD! Pleurodira" Cryptodira" slide from J. Wiens Turtle phylogeny! based on molecular data ! (Krenz et al. 2005)! Trionychid ae" Geoemydid ae" Testudinida e" Emydida e" Carretochelyid ae" Cheloniid Kinosternidae" ae" Dermochelyid Dermatemydid ae" ae" Chelydrida e" Platysternonida e" TSD! GSD! Podocnemidae" Pelomedusidae" Chelidae" •  Pleurodira" Cryptodira" Was TSD present in the ancestor of all living turtles?" slide from J. Wiens TSD/GSD" " •  Why does it evolve and why is it maintained? " " •  Not en0rely clear what the advantage might be for having TSD slide from J. Wiens TSD/GSD" •  Not entirely clear what the advantage might be for having TSD" " •  " " One hypothesis based on theory (Charnov and Bull 1977 Nature 266:828)" •  TSD will evolve if: there are effects of developmental temperature on fitness which are different in each sex and if TSD causes each sex to be produced more often at the temperature at which that sex has higher fitness" •  Example if males have an advantage when they develop at low temperatures, could favor TSD that produces more males at lower temperatures" slide from J. Wiens TSD/GSD" Testing Charnov-Bull model" •  " "Important study by David Warner and Rick Shine "published 2008 in journal Nature " •  Tested predictions of Charnov-Bull model in a shortlived Australian agamid with TSD (Amphibolorus muricatus)" •  Incubated eggs at different temperatures (23, 27, 33º C), but manipulated sex by using hormonal treatments, determined fitness of each sex at different temperatures" slide from J. Wiens TSD/G...
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